1. Field of the Invention
The present invention relates to a method of operating a (CT) computed tomography device, by means of which volume data with respect to a volume region of a test object can be recorded.
2. Description of the Prior Art
Normally, before the definition of a region with respect to which volume data are to be recorded, for example by means of a spiral scan, an X-ray shadow image (topogram) is recorded, using which the scanning area of the following spiral scan is defined graphically. The definition of a scanning area is carried out by means of graphical marking of a region, inter alia a rectangular region, in the X-ray shadow image, which includes the interesting region of the test object. The length of the rectangle defines the length of the spiral scan, the width of the rectangle defines the width of the field of view represented in the CT image.
When defining a number of spiral scans, the above procedure is applied repeatedly.
German OS 199 25 395, which claims earlier priority but is not a prior publication, discloses a method of operating a CT device, in which volume data obtained in the course of a volume scan is used to extract the data needed for the reconstruction of an X-ray shadow image.
U.S. Pat. No. 5,995,580 describes a method of reconstructing volume data pertaining to a volume region that is limited in the direction of the system axis of a CT device, in which the start and end surfaces of the volume region are curved.